Ubuntu 22.04 LTS must automatically lock an account until the locked account is released by an administrator when three unsuccessful logon attempts have been made.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
low	V-260549	SRG-OS-000021-GPOS-00005	UBTU-22-411045	SV-260549r958388_rule	2025-03-03	2

Description
By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, otherwise known as brute-forcing, is reduced. Limits are imposed by locking the account. Satisfies: SRG-OS-000021-GPOS-00005, SRG-OS-000329-GPOS-00128

ℹ️ Check
Verify that Ubuntu 22.04 LTS utilizes the "pam_faillock" module by using the following command: $ grep faillock /etc/pam.d/common-auth auth [default=die] pam_faillock.so authfail auth sufficient pam_faillock.so authsucc If the "pam_faillock.so" module is not present in the "/etc/pam.d/common-auth" file, this is a finding. Verify the "pam_faillock" module is configured to use the following options: $ sudo grep -Ew 'silent\|audit\|deny\|fail_interval\|unlock_time' /etc/security/faillock.conf audit silent deny = 3 fail_interval = 900 unlock_time = 0 If "audit" is commented out, or is missing, this is a finding. If "silent" is commented out, or is missing, this is a finding. If "deny" is set to a value greater than "3", is commented out, or is missing, this is a finding. If "fail_interval" is set to a value greater than "900", is commented out, or is missing, this is a finding. If "unlock_time" is not set to "0", is commented out, or is missing, this is a finding.

ℹ️ Check

Verify that Ubuntu 22.04 LTS utilizes the "pam_faillock" module by using the following command: $ grep faillock /etc/pam.d/common-auth auth [default=die] pam_faillock.so authfail auth sufficient pam_faillock.so authsucc If the "pam_faillock.so" module is not present in the "/etc/pam.d/common-auth" file, this is a finding. Verify the "pam_faillock" module is configured to use the following options: $ sudo grep -Ew 'silent|audit|deny|fail_interval|unlock_time' /etc/security/faillock.conf audit silent deny = 3 fail_interval = 900 unlock_time = 0 If "audit" is commented out, or is missing, this is a finding. If "silent" is commented out, or is missing, this is a finding. If "deny" is set to a value greater than "3", is commented out, or is missing, this is a finding. If "fail_interval" is set to a value greater than "900", is commented out, or is missing, this is a finding. If "unlock_time" is not set to "0", is commented out, or is missing, this is a finding.

✔️ Fix
Configure Ubuntu 22.04 LTS to utilize the "pam_faillock" module. Add or modify the following lines in the "/etc/pam.d/common-auth" file, below the "auth" definition for "pam_unix.so": auth [default=die] pam_faillock.so authfail auth sufficient pam_faillock.so authsucc Configure the "pam_faillock" module to use the following options. Add or modify the following lines in the "/etc/security/faillock.conf" file: audit silent deny = 3 fail_interval = 900 unlock_time = 0

✔️ Fix

Configure Ubuntu 22.04 LTS to utilize the "pam_faillock" module. Add or modify the following lines in the "/etc/pam.d/common-auth" file, below the "auth" definition for "pam_unix.so": auth [default=die] pam_faillock.so authfail auth sufficient pam_faillock.so authsucc Configure the "pam_faillock" module to use the following options. Add or modify the following lines in the "/etc/security/faillock.conf" file: audit silent deny = 3 fail_interval = 900 unlock_time = 0